<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <link rel="stylesheet" type="text/css" href="DiscScheduling.css">
    <title> Disc Scheduling </title>
</head>

<body>
    <div class="topnav">
        <a class="active" href="index.html
        ">Home</a>
    </div>

    <h1 class="heading">What is meant by Disc Scheduling?</h1>
    <p>
        Disc Scheduling is done by operating systems to schedule I/O requests ariving for the disc. It is also known as
        I/O scheduling.
        Disk scheduling is important because: Multiple I/O requests may arrive by different processes and only one I/O
        request can be served at a time by the disk controller.
        The main aim of Disc Scheduling algorithm is to reduce or minimize the seek time for a set of requests.
    </p>

    <div class="list">
        <h2>Here are some of the important terms used:</h2>
        <ol>
            <li>
                <b>Seek Time:</b> The time taken for the disc arm to locate a specified data track where the data is to
                be
                read or write.
            </li>
            <li>
                <b>Rotational Latency:</b> It is time taken by the desired sector of disc to rotate into a position such
                that it can access read/write
                heads.
            </li>
            <li>
                <b>Transfer time:</b> The time taken to transfer the data.
            </li>
            <li>
                <b>Disc access time:</b> Disc Access time = Seek time + Rotational latency + Transfer time
            </li>
            <li>

                <b>Disc response time:</b> Response Time is the average of time spent by a request waiting to perform
                its I/O operation.
            </li>
        </ol>
    </div>

    <br>


    <h2>Disc Scheduling Algorithms:</h2>
    <ul class="block">
        <b>FCFS</b>
        <p>First Come First Serve, as the name implies, addresses the requests in an orderly manner of which they arrive
            in the disc.
            It is one of the simplest of Disc Scheduling Algorithms.
        </p>
        <button class="button"><a href="fcfs1.html">Simulate</a></button>
    </ul>

    <ul class="block">
        <b>SSTF</b>
        <p>Shortest Seek time First; whose basic idea is the tracks which are closer to current disk 
            head position should be serviced first in order to minimise the seek time operations.
        </p>
        <button class="button"><a href="sstf1.html">Simulate</a></button>
    </ul>

    <ul class="block">
        <b>SCAN</b>
        <p>SCAN is also known as <i>Elevator</i> algorithm. In this head starts from one end of the disk and moves towards the other end, 
            servicing requests in between one by one and reach the other end. 
            Then the direction of the head is reversed and the process continues as head continuously scan back and forth to access the disk.
        </p>
        <button class="button"><a href="scan1.html">Simulate</a></button>
    </ul>

    <ul class="block">
        <b>CSCAN</b>
        <p>The circular SCAN (C-SCAN) scheduling algorithm is a modified version of the SCAN disk scheduling algorithm. 
            C-SCAN moves the head from one end servicing all the requests to the other end. However, as soon as the head reaches the other end, 
            it immediately returns to the beginning of the disk without servicing any requests on the return trip and starts servicing again once reaches the beginning. 
        </p>
        <button class="button"><a href="cscan1.html">Simulate</a></button>
    </ul>

</body>

</html>